Waterborne Polyurethane Prepolymers

The demand for waterborne polyurethane coatings is surging day by day with large number of users using it for the trade coating of wood and parquet floors. Their quality of producing very small amount of volatile organic compounds (VOC) makes them every useful. They are almost odorless and are almost nil polyurethane dispersion available that do not contain N-methyl pyrrolidione (NMP).

It is obvious that new waterborne polyurethane prepolymers require less co-solvent to produce good coatings than the products containing NMP. The waterborne polyurethane coatings are in huge demand due to their unmatched resistance to abrasion and high mechanical resistance properties.

Nowadays, the manufacturers have developed the new polyurethane dispersions by replacing the old polymer mixing process which includes NMP as a solvent with the acetone process. The acetone process requires adjusting the recipes for the dispersions to be responsible for the lower solvent power of the acetone, which is distilled off following the creation of the prepolymer to get a solvent-free product.

Waterborne polyurethane prepolymers offer excellent chemical resistance and high finish. The final product can be used separately or in association with NMP-free polyurethane dispersions as the A component in two-component systems.

Numerous Advantages of Polyurethane Prepolymers

Although there are numerous products in the market that are being used for various commercial and personal projects but Polyurethane Prepolymers have their own value and importance. The latest series consist of aromatic polyurethane prepolymers generally used in the production of coatings, sealants, and adhersives.
Under the process, curing takes place by direct contact with atmospheric moisture to deliver tough, resilient polymers with outstanding durability.
The various applications include:
• Sports and Playground Surfacing
• Rubber Crumb Binder
• Dust sealer for Concrete
• Hard, Tough Floor Coatings
• Polyurethane Sealants
• Polyurethane Adhesives
Another kind of prepolymer consists of alipathic polyurethane prepolymers generally used in the production of sealants, expansion joints, coatings and adhesives.
Here curing takes place by direct contact with atmospheric moisture by use of an oxazolidine latent hardener.
The typical applications of this polymer include:
• Adhesives
• Sealants
• High Performance Coatings
• Block Paving Seal
• Concrete Sealer
• Wood Lacquers

Waterborne polyurethane dispersions, extensively used in coatings & adhesives

There are various types of coatings, which are used extensively in personal as well as commercial constructions sites. There are Metal coatings, leather coatings, garage floor coatings, swimming pool coatings, extreme trailer coatings and concrete densifier and sealer coatings. And the power which these materials have is helpful in resisting household chemicals, mechanical shocks and scratches and this is one of the paramount reasons to use epoxy floor coatings. People often use waterborne polyurethane dispersions for their garage floors, where cars, chemical treatments and heavy pieces of furniture and equipments.

Water bond epoxy floor coating cannot hide cracks, however they are user-friendly. Water based epoxy floor coatings are generally used for residential purposes, whereas industrial and rough coat epoxies are suited for commercial and industrial uses. Water based epoxy floor coating is perfect for garages and is both a primer and a topcoat.

Epoxy, polyurethane, acrylic sealer or stain or latex c are different types of garage floor coatings. Epoxy forms a durable surface and bonds well the concrete under it. Chemical spills can be resist by polyurethane can resist. Acrylic sealers or stains are like latex paints are inexpensive and make it look great. By using these waterborne coatings we can escape the garage floor from a lot of wear and tear and make it look wonderful.

Polyurethane Prepolymer used to make expansion joints and adhesive

Polyurethane Prepolymer is generally used in the production of sealants expansion joints, coatings and adhesives. Whether for personal or commercial construction, these materials are used extensively. The situations of cracks and gaps are pretty normal and they become more visible after getting into the direct contact with atmospheric moisture, or more often by use of an oxazolidine latent hardener. To avoid these cracks and gaps, people often use polyurethane prepolymer for filling expansion joints and for coating and adhesive purposes.

Generally polyurethane prepolymer includes Adhesives, Sealants, High Performance Coatings, Block Paving Seal, Concrete Sealer and Wood Lacquers. All these materials are very helpful in protecting garage floors, where cars, chemical treatments and heavy pieces of furniture and equipments. By using these coatings and adhesive we can escape the garage floor from a lot of wear and tear and can provide it very magnificent appearance. These materials can also provide protection from carbon dioxide gassing in high humidity conditions and all grades are suitable for use.

So to escape from the situation of cracks and gaps, you better move towards buying such adhesive coating materials. You can buy them from a reputed online seller and that too in an affordable price range.

Oxazolidines: Latent Curing Agents

The latent curing agents are meant for use in a wide range of coatings, adhesives, and sealant applications. They are proved to be very beneficial in conditions that require high build properties. For instance, waterproof coatings and construction sealants. Oxazolidines are used as latent curing agents and can be used in both one and two component PU systems.

In case of one component PU system, these latent curing agents are generally used with aliphatic prepolymers. They enhance fast through-cure with no carbon dioxide gas evolution. On the exposure to moisture, these agents get hydrolysed, yielding reactive amine and hydroxyl functional groups.

The unique properties of these latent curing agents are primarily determined by the curing mechanism, which is entirely different from the conventional “moisture cure” reaction. During this process, moisture reacts directly with the terminal isocyanate of the prepolymer producing gaseous carbon dioxide. It results in blisters and bubbles in the coating film.

Moisture primarily reacts with the oxazolidine rather than with the prepolymer’s terminal isocyanate groups. The underlying process of hydrolysis and ring opening of the oxazolidine generates amine and hydroxyl groups. These amine and hydroxyl groups then subsequently react with the isocyanate of the prepolymer without the evolution of carbon dioxide gas.

Reactive Diluents for Flexible Polyurethane Coatings

Because of the presence of VOC content in paints and coatings, formulators have faced a serious challenge – how to develop a high-solids polyurethane system that has low viscosity for easy usage as well as optimum performance while complying with regulations.

One answer to this question in the use of low-molecular weight polyols to create a lower-viscosity formulation that needs less solvent. Unluckily, reductions in polyol molecular weight often lead to systems that support cure too quickly and don’t perform well in the field. In case of the absence of molecular weight reductions, polyols essentially have the tendency of high intrinsic viscosities, which make it very difficult to remove solvent from the formulation.

Reactive diluent are low-viscosity coreactants that are developed specifically to reduce VOCs through a reaction with the polymer matrix. As solvents, they lessen polymer viscosity without increasing VOCs.

Reactive diluents normally take the form of blocked or concealed sources of active hydrogen. Aldimines and ketimine are instances of blocked amino compounds. Oxazolidines are a good example of blocked amino alcohols. Aldimines and hampered amines are generally quite low in viscosity (less than 5,000 cps at 100 percent solids). They are quick reactive with isocyanate and often suffer from uninvitingly lessen pot life. Even then, they still remain quite attractive for applications where highly rapid cure is required.

Waterborne Curing Agents: Demand on All Time High

Now-a-days, there are a number of companies which are in the manufacturing of specialist resins and polymers. Now, when it comes to waterborne curing agents, these agents are used for emulsifying and hardening both liquid and solid epoxy resins, thus yielding tough and durable polymers.

These companies opt for continued research in the field and come out with an excellent range of waterborne curing agents. These high performance materials are in high demand and are mostly used for coatings, sealants, elastomers and adhesives, all over the globe.

As is clear from the recent market trends, the demand for these waterborne curing agents is stretching across the global market. To meet the ever-growing demand for these products, more and more companies are now planning to expand their networks. This also helps these companies to maximize their market presence and earn huge profits. What’s more, they also offer tailor made solutions to their customers, with an eye on continuous improvement.

More information about these waterborne curing agents can be gathered with the help of internet. Most of the companies, manufacturing these agents and other high performance materials, put all the essential information about their products on their websites.

Benefits of Waterborne Epoxy Curing Agents

The waterborne epoxy curing agents can be used to soften and harden both liquid and solid epoxy resins, yielding tough, durable polymers. These agents act an adhesive to damp concrete. They have water vapor permeability.

Polyurethane Prepolymers are widely used in the production of coatings, sealants and adhesives. In this case, curing takes place by direct contact with atmospheric moisture to deliver tough, resilient polymers with extraordinary durability. There are several applications of these waterborne epoxy curing agents including sports & playground surfacing, rubber crumb binder, dust sealer for concrete, polyurethane sealants and polyurethane adhesives.

Some waterborne curing agents undergo a chemical reaction with the epoxy resign to yield a tough, durable coating. It results in good stability and epoxy compatibility. It offers total compatibility with cement and calcium salts. Their applications include floor and wall coatings, anti-corrosive primers, self-leveling systems, high gloss coatings, clear lacquers, and epoxy floor screeds.

Epoxy Repair Mortars are waterborne reactive polyamine adducts with long pot life and low viscosity. It has complete compatibility with cement and calcium salts. It is well suited for high temperature climates. The applications include floor and wall paints, hygiene coatings, epoxy cement mortars, concrete primers, gloss paints and green concrete coatings.

Oxazolidines as Latent Curing Agents

Latent curing agents are used in a wide variety of coating, adhesive and sealant applications. These curing agents are particularly beneficial where high build properties are required, for say waterproof coatings and construction sealants. This range of curing agents can be used in both one and two component PU systems. They are normally used with aliphatic prepolymers in one component systems. They promote fast through-cure with no carbon dioxide gas evolution. The curing agents hydrolyse on exposure to moisture, yielding reactive amine and hydroxyl functional groups.

While in two component systems they can be also be used with aromatic prepolymers or isocyanates.

The range of latent curing agent consists of Incozol 4, which is a standard bis-oxazolidine curing agent, Incozol HP is a high purity curing agent plus Incozol NC & Incozol K which are non-crystallising curing agents.

Curing Mechanism

The curing mechanism, which differs from the traditional "moisture cure" reaction, chiefly determined the unique properties of the latent curing agents.

Moisture reacts directly with the terminal isocyanate of the prepolymer generating gaseous carbon dioxide inn this process. This results in blisters, bubbles or foaming in the coating film.